I did pretty much the same thing. You can beat him by grabbing a laser rifle and a heavy machine gun. Run to a corner on the outer ring of sculptures and wait for Namir to show up and start sniping you with his plasma rifle. Once he does that, just snipe back from cover with the laser rifle. He won't change position as long as you two keep this up, and eventually he'll die. You may next want a tuturial on how NOT to punch your screen after your upcoming encounter with Megan. that skank. Hope it helps.