You'll need to give more information on which footprint you need and how this device is being used. Generally, to find a substitute:
1) Ensure the footprint/pin-out is the same
2) Make sure the Vgs, Rds, Vdss, and Power are the same or better.
3) Make sure the new device is also a p-channel MOSFET.
Most manufacturers allow you to search by parameters. Digi-Key also has a fairly good parameter search.