Go Google which relics you need to have the best chance then Google where you have the best chance to get those relics. Then go farm some points to radiant them (althoug IMO that does not help a whole lot). Then do endless relics missions to get the parts, don't solo it, go in with a team, you have more choice and someone else might use the same relics increasing your odds. Also I say endless missions because they give more rewards the longer you play and they often also give you new relics. As a tip I could say that IO is the best mission to get Meso relics and it is also good to get Neo relics if you stay longer than 2 turns and IO is often on rotation for Meso relics so it is a good one to do for the Meso parts.