I don't think you will be able to do it with your mesh you need to transfere to a new mesh, try doing as I have done, create a plane the same size as your mesh I have 4 faces you will have 16 assigne a different shader to each face (this is so will can extract the part later) now increase the poly count to what you need then select the modelled part first hold down ctrl and select the plane next now go to mesh/transfere attribute and put in the settings I have, after you have done that delete the history of the new mesh. You can now select each face area by going to the shader and doing a duplicate or extract.........dave

Edit: Should share the same space when you do the transfere attributes