Loud clicking/ticking in engine

1998 Pontiac Sunfire convertable w/80,000 miles.
Running with very low or almost no oil for a short distance. Didn't overheat but makes a loud clicking, ticking noise. Replaced oil filter and oil didn't see any metal shavings. Was told maybe it was a loose rod or broken rod. What should I look for or have someone look for? Will I have to replace the whole engine or just those parts? Only have had the car two months for my son so would be disappointed if had to replace the engine already.