Q: Temperature went up when I turn on the AC

I was on my way home after driving for 25 minutes through a highway, then when I was approaching a light, I decided to turn on my AC. At the beginning I realized it wasn't cooling, and I wondered why? after a couple minutes (1 mile or two miles) I saw that the car temperature went up. I immediately turned off the AC and fan. I could notice that the temperature tended to went down when I stopped the car, for instance at a light, but when I started to speed, it went up again. I parked the car, opened the hood and I could see a little smoke coming from the radiator area. ( I am not sure where exactly but it was in front of the motor where the radiator is). I also saw that some liquid was spilled on the surface of radiator (just a little bit) and some drops were on the floor. This is the first time I see this in my car. The AC was working well until today that this happened to me, so I would like to know what the possible problems are.

My car has 108500 miles.
My car has an automatic transmission.