The close to central park location of this famous musuem makes it easy to include it your travel plan. Every friday from 16:00 to 20:00 the MOMA is completely free - including the wardrobe.
Just go there, grab one of the free tickets with are displayed in the main hall and go for it. If you are in to moderna rt you will love it and 4 hours are probably not even enough. But for most people its enough time to visit this hugh musuem with its big exibitions.
Even if you are - like myself - not an expert or fan of modern art - you will enjoy the big variety of the MOMA. And its one of the "Must Sees" in NYC. MOMA website