<form action="dosearchsite.action" method="get">
<input type="radio" name="queryString" value="labelText:">Label<br>
<input type="radio" name="queryString" value="title:">title<br>
<input type="text" name="queryString">
<input type="submit" value="Submit">
</form>

$('#form-id').submit(function(e){
 e.prevetDefault();
 $.get(url, { queryString: $('#form-id input[name="queryPrefix"]').val()+$('#form-id input[name="queryString"]').val() });
});