...

$("#list").jqGrid('searchGrid', {multipleSearch:true} );

<div class="fikket_grid span 14 last">            
    <!-- the grid definition in html is a table tag with class 'scroll' -->
    <table id="list" class="scroll" cellpadding="0" cellspacing="0"></table>
    <!-- pager definition. class scroll tels that we want to use the same theme as grid -->
    <div id="pager" class="scroll" style="text-align:center;"></div>                
</div>

<script type="text/javascript">
    $(document).ready(function(){
        $("#list").jqGrid({
            width: 900,
            height: 240,
            autowidth: false,
            rownumbers: true,
            rownumWidth: 40,
            url:'<?php echo $this->baseUrl() ?>/incometypes/list',
            datatype: 'json',
            mtype: 'POST',
            colNames:['ID','Description','Budget Amount','Budget Period'],
            imgpath: '<?php echo $this->baseUrl() ?>/js/themes/coffee/images',
            colModel :[
                {name:'id', index:'id',
                    width:10,
                    hidden:true
                },                
                {name:'income_types_desc', index:'income_types_desc',
                    width:50,
                    sortable:true,
                    editable:true,
                    editoptions:{size:20}
                },
                {name:'income_types_budgetamount', index:'income_types_budgetamount',
                    width:30,
                    sortable:true,
                    editable:true,            
                    editoptions:{size:20},
                    search:true,
                    searchoptions:{sopt:['eq','ne','lt','le','gt','ge']}                    
                },
                {name:'income_types_budgetperiod', index:'income_types_budgetperiod',
                    width:40,
                    sortable:true,
                    editable:true,
                    edittype:"select",
                    editoptions:{value:"<?php echo $values?>"}                                        
                }
            ],
            pager: $('#pager'),
            rowNum:10,            
            rowList:[10,20,30],
            sortname: 'income_types_desc',
            sortorder: "asc",
            viewrecords: true,
            viewsortcols: [true,'horizontal',true],
            gridview: false,
            hidegrid: false,
            editurl:"<?php echo $this->baseUrl() ?>/incometypes/edit",
            caption: 'Define Your Various types of Income',
            forceFit : true
        });                    
        $("#list").jqGrid('searchGrid', {multipleSearch:true} );       
        $("#list").jqGrid('navGrid','#pager',                                
                {add:true,addtext:'Add',edit:true,edittext:'Edit',del:true,deltext:'Delete',search:true,searchtext:'Search',refresh:true,refreshtext:'Refresh'},                
                {url:'<?php echo $this->baseUrl() ?>/incometypes/edit',
                closeAfterEdit:'true'},
                {url:'<?php echo $this->baseUrl() ?>/incometypes/add',
                closeAfterAdd:'true'},                                                               
                {url:'<?php echo $this->baseUrl() ?>/incometypes/delete',closeAfterAdd:'true'},
                {closeOnEscape:true, multipleSearch:true, closeAfterSearch:true }                                                    
              );    
    });

</script>