Routing A List of Predefined IPs Over VPN Interface

Hi,

I already have a RB2011UAS2HnD-IN router that is using my VDSL2 modem for PPPoE.

I lıve in Turkey and some websites (including twitter) are blocked due to political reasons.

I already have OpenVPN running on a Ubuntu VPS and successfully connect to the VPN server on my computers and mobile devices using the native OpenVPN client. On the other hand no matter how hard I tried, I could not succeed to connect my router to my openvpn server.

What I actually want to do is, route traffic for a predefined list of ips over a vpn interface, and for remaining traffic use my default gateway so I can benefit from my 100mbps connection speed.

Because I have full control over my vps, i have the ability to install any VPN software that is available for Linux. My question is; what is the best VPN solution that can work in this scenario and how I can set it up in my mikrotik router?

Thanks.