He's a frame overo. He "could" have sabino or splash, but I don't see it - frame can often affect the legs as well, and the shape of his pattern screams frame overo all the way to me.
Example of the range for frame overos. They are called frames because the color frames the white which is usually restricted to the barrel of the horse, a splashy head and a couple legs.
Frame works by manipulating other pattern genes, and is not known for producing extreme leg white by itself, especially where it is connecting up to the belly like that. Her horse is far too loudly patterned to only be carrying Frame. A lot of the horses in that diagram are Frame + another gene.
Overo, most definitely...um, which type, I guess, you'd have to get him tested to determine exactly what types he has. My guess would be frame, and sabino...
Frame Overo + Sabino. Sabino is usually what gives the laced edges and "roaning." The tall white sock that connects up the back leg lends itself to Sabino as well.