Question
Can you pray namaaz with short sleeves/vest?
What about 3 quarter trousers?
Answer
The satar of a male which must be covered during salah and if exposed the salah would be invalid is from the navel to below the knees. Covering the other parts of the body is desirable; leaving them exposed will be disliked (makrooh). The Prophet sallallahu alayhi wasallam and the Sahabah radiallahu anhum would cover their whole bodies, often with two large sheets. So in your question the salah would be valid; if the arms and the shins were exposed due to poverty and not possessing proper clothing, then there would be no harm, but if clothes were available and you still did not cover the entire body, then the salah will be makrooh, which means that the reward will be heavily reduced.