This assumes both machines, server and client, are on the same network and the port that will be used is open for network connections.
Assuming you already have docker installed
vi /lib/systemd/system/docker.service
Modify the following line:
ExecStart=/usr/bin/docker daemon -H fd:// -H tcp://0.0.0.0:2375
sudo systemctl daemon-reload
sudo systemctl restart docker.service
Check it's working by running:
curl http://localhost:2375/version
export DOCKER_HOST="tcp://192.168.2.196:2375"
And that's it. From now on, docker commands on the client will execute on the server.