My Doctor Told Me That He Could Not Remove my Lipoma Wholly- He Took out in Pieces

Without seeing photos, it is difficult to evaluate your question. It is possible that your lipoma was unencapsulated which is differentiated from a fat collection or a discrete mass. These lipomata have special challenges and, under those circumstances, the surgeon may have opted not to remove the entire mass in a single procedure.

The anatomy in the neck is delicate.  Your surgeon may have felt that it was safer to piecemeal the lipoma out with remnants that as one piece.  If it is a lipoma, is likely to recur but it will take time to do so and will be gradual.

The neck is a very complex anatomical structure. If your lipoma was under the muscle in the neck and your surgeon felt that it is safer to approach the surgery that way than dive into a complex surgery with potential severe risks. Then he/she did the right thing.

Wait for the pathology results. If it is a lipoma, then the worst thing that could happen is for the lipoma to come back some time in the future.