redirect-gateway option may or may not change the gateway for reaching the OpenVPN server, depending on the flags provided to it.
According to man page of
local -- Add the local flag if both OpenVPN servers are directly connected via a common subnet, such as with wireless. The local flag will cause step 1 above (Creation of a static route for the --remote address which forwards to the pre-existing default gateway) to be omitted.
So, just add a
redirect-gateway local option in client config file, to override the pushed option. This will cause
openvpn to just add a new default route, and not a specific route for the server. So the current route being used to connect to ther server will continue to be used.
If you want this behavior for all clients, edit the server config file and change the option
push "redirect-gateway" to
push "redirect-gateway local".