There are several ways to stop a leak in a pipe. For a temporary patch, use a piece of heavy rubber and hose clamps or a rubber pad and two plates that bolt together.
You'll find patch kits for plumbing leaks at the hardware store, or you can make your own with a piece of heavy rubber from an old inner tube and a C-clamp. Another possibility is to use a hose clamp with a rubber patch. Factory-made kits contain a rubber pad that goes over the hole in the pipe and metal plates that compress the rubber pad over the hole. A quick and easy way to stop a leak, the patch kit can even be used on a permanent basis if the pipe is otherwise sound.