The code like following could solve your problem
$("#customer_list").jqGrid ('navButtonAdd', '#customer_list_pager',
{ caption: ""/*"Show"*/, buttonicon: "ui-icon-extlink", title: "Show Link",
onClickButton: function() {
var grid = $("#customer_list");
var rowid = grid.jqGrid('getGridParam', 'selrow');
window.location = grid.jqGrid('getCell', rowid, 'dataUrl');
}
});