You can try this:

var gr = new GlideRecord("sc_req_item");
gr.addQuery("u_requested_for", g_form.getValue("emp_name"));
gr.addQuery("stage",'!', "waiting_for_approval");
gr.query();
if(gr.next())
{
alert("A request has already been submitted by " + gr.opened_by.name); // this is returning sys_id, I need the value
}