is there any way to seal a leak in a Radiator?

i got a 120MM radiator from someone on another forum. Started leak testing it and it starts leaking all oover the place. There were four drill holes where the previous owner decided to drill into the fins to mount a fan . well anyway it seems that it went a little too far and hit the core part. Is there anyway to seal it? can you take apart radiators? it seems i am at a loss currently.
pic of the radiator from the seller, you can see where he drilled the holes i shoulda paid attention before i bought it : .

I imagine an automotive radiator repiar shop could fix that, as it is in fact a heatercore, but I could be wrong. Couldnt say how much it would cost.
You don't happen to live in the states, do you? If you did, you could replace that piece for like $10 at an auto parts store.

Get some JB Weld, it has two tubes you mix and it is like a cold solder. I used it a couple of days ago to fix my current rad.

If the leak is between the tubes, soldering is going to be tricky. JB weld is a better bet. Be sure you get the area around the hole very clean.