You will receive equipment points for upgrading your rooms. You will receive these patients in addition to your regular patients, if you improve your rooms and beds by upgrading them. On having reached 12 equipment points, you will receive 1 additional patient; from then onwards, you will receive one new patient every 12 points, so at 24 points, 36 points, and so forth.
For further info on how to get new patients, just visit the Forum and read the FAQ-section on rooms.