Oh yeah, breaking out the big tips here. Here's the thing, though: you have to be quick once you start. It doesn't really matter what fabric it got onto, though I would proceed with EXTREME caution with cheap or delicate clothing.
It doesn't matter if it's dried or not. Well, it does a bit, but bare with me.
You go and buy oil paint thinner from your local art store. It HAS to be fine arts quality paint thinner. they usually smell like oranges or some BS that tries to tell you it's not ACTUALLY a harsh chemical (it's a lie!). Oil paint thinner is in of itself, oily, so you need to be able to remove IT after you're done. So aside from the thinner, you will need a face cloth, and a bowl of hot water and dish soap.
Now listen. If you let the paint dry on the fabric, the thinner will still get it out, but you will have to let the thinner sit on the fabric for a couple of minutes. If the fabric has cheap dye, it will fade under the thinner. If the fabric is plastic based, it may wear from this, so a) be careful where you apply it and try to get it ONLY on the paint and b) proceed with caution and know the longer it sits, the more it dissolves.
If the paint is wet, great! You simply wipe a good amount of the thinner into the affected area. Scrub with fingertips quickly, get that paint worked up, and then use the cloth and the soapy water to QUICKLY scrub the paint and thinner out of the fabric. This will work. It will come out easily. The quicker you get the thinner out of the fabric, the less fading and wearing it will do. You have about 30 seconds before it will start making a difference in any way, so move quickly and your clothes will be just fine. I have taken 2 year old oil paint right out of thick carpeting no problem doing this.
I'm not responsible for any stupid happenings that may be a result of this. Use your brain, don't do this on a $200 jacket. Also, don't paint while wearing a $200 jacket. Or near a $200 jacket. Practice safe painting.