I would look closely at the backing plate to rotor clearance. Sometimes when you are messing around in there, you push or pull on the backing plate and it touches the rotors. On the rears, the backing plates have a tendancy to rust out and start dragging on the inside of the brake rotors. I have done a bunch of those.
If you had any silencer pads that you transferred from the old pad to the new, sometimes they slip off and get trapped by the caliper/ bracket/rotor and they scrape. Also the slider pads/spacer that the pads ride on, on the caliper bracket, they might have gotten tweaked when putting in the pads and they start to scrape the rotor.
If you can, isolate the side where the noise is coming from and then go back over the brake job on that side and take a good look around.
As Kaotik has said, it could be a loose/worn hub that lets the wheel flop around when loaded, like in a turn, and the brake rotor rubs the backing plate. If the hub were that worn, you should be able to shake the wheel/hub assembly with the wheel off the ground. Also, there will be a noise when driving. That'll be noticable. Good luck and keep us posted.
