how to validate any one field in form

In my form i want to validate one field mobile or phone which are user want to fill. if user want to fill mobile filed then phone field is not required. and if user want to fill phone field then mobile field is not required.

my script is..............

<script type="text/javascript">
$(function(){
$("#test_formss").validateset({
rules: {
mobiless: { required: true, number: true, minlength:10, maxlength: 10 },
phoness: { required: true, number: true, minlength:7, maxlength: 15 },
},
messages: {
mobiless: { required: "This Field is Required" },
phoness: { remote: "This Field is Required" },
}
});
});
</script>
<div>
<form name="test_formss" id="test_formss" action="" method="post" enctype="multipart/form-data" onSubmit="return validateset();">
<input type="text" name="mobiless" id="" value="">
<input type="text" name="phoness" id="" value="">
<input type="submit" name="check_send" id="check_send" value="Submit">
</form>
</div>