If it asks for a part 116, the archive is incomplete. To give you more specific instructions, could you tell me: Do you have all 115+ parts of this archive? What error message are you seeing, if any?
This format requires all parts (1 through 115) to be present in the same folder to reconstruct the original data [1]. 500.part115.rar
are you using (Windows, macOS, Linux)?
Multi-part files are often password-protected. Ensure you have the password from the source. If it asks for a part 116, the archive is incomplete