Im trying to replicate the drilling holes which can be found on climbing walls. They are uniform in shape and should tile with the same distance and should not be cut on corners (getting half holes for example). I've tried different methods like using a texture and using different nodes (polka dot generation with all sort of different math nodes) to replicate this effect but none of them seem to do the thing I want to do or I get some weird black mesh results and it srews up (I am also pretty new to Blender and not very good at it).
This is an example of what I want to achieve.
My question is, what would be the best method and how would I achieve this? cutting physical holes in the mesh, or make a texture with some sort of bump/displacement mapping since the camera is a bit in the back and does not really show the actual holes from a distance.
Be advised that my mesh is not just one flat surface but consists of different surfaces with different angles. This is what I currently have; 
preferably I'd use the node editor (im using cycles render engine) for maximum control but I haven't found any decent solutions which actually make it sort of look like the holes I want them to be. If anyone has some sort of solution or can point me in the right direction that would be much appreciated.