sounds like a diseal engine.

make sure you check the engine oil level first. If it is OK the problem may be due to a lack of lubrication to components internally in the engine. Internal oil passages may become b locked if the engine oil is infrequently changed. Your engine has hydraulic valve lifters, if they get "gummed up" inside or fail they result is a very "clattery" sounding engine. Does your oil light/oil pressure gauge work properly? Safest to get someone knowledgeable with cars to give their opinion and or get a garage to check out the noise and possible prevent further damage.