It depends on the person and their injury. A physician would always be a good idea to start with, but other options would be to either eliminate pushups for the moment and see if the pain goes away or start using other equipment (like the ones you have mentioned in your question) so it can take some pressure off their wrists. Elevated push-ups could be another option for your client or even the usage of bands and/or TRX to add some chest presses. Once they get stronger doing push-ups on an elevated surface (bench, steps, boxes, etc.) then you can start moving them lower to the ground until they can do them without any discomfort and/or pain.