Docker: OpenVpn Server

Got an Ubuntu machine with multiple NICs. Want to have an OpenVPN with access to multiple network interfaces. Each client has access to only one predetermined NIC. No limitation how the problem will be solved: e.g. - Multiple instance of openvpn (docker containers) - One instance of OpenVPN with multiple NIC configuration. Think the docker option will be better as Intend to add more NICs Either way I would need detailed instructions as I am not a networking expert.