Noise coming from my engine.

Hi. I have a 2004, 4 cylinder Toyota Corolla LE Automatic, with about 67,000 miles. Recently I my oil indicatorstarted to flicker on and off, when I check the oil stick I was almost out. So I added a little bit of oil to the car, so that it kept me going, then a week later the light started to flicker again, this time the oil indicator light remained on, so again I added a little bit more oil, but the oil indicator light still remained on. Now my engine is making a clack clack clack clack noise everytime I push down on the excellerator, and my check engine light has gone on. When I pick up speed the noise leave, but when I stop and try to start up again that is when you hear the clack clack clack clack noise. Can you please help me out.