To let the engine know how it should break your mesh, you need to provide an impulse direction vector and a hit location. You can do that with the ApplyDamage node:
https://docs.unrealengine.com/en-US/…age/index.html
You should probably create a Blueprint for your destructible mesh and override the ‘OnClick’ event, and then use world location of the actor to construct the vectors that can be used as a hit location and impulse direction in the ApplyDamage node.
This is just a high level overview of this approach, to get a more detailed answer you should let us know where did you get stuck.