You usually don't want to do this. With Docker Compose you define services that compose your app. npm and manage.py are just management commands. You don't need a container for them. If you need to, say create your database tables with manage.py, all you have to do is:
docker-compose run client python manage.py create_db
Think of it as the one-off dynos Heroku uses.
If you really need to treat these management commands as separate containers (and also use Docker Compose for these), you could create a separate .yml file and start Docker Compose with the following command:
docker-compose up -f my_custom_docker_compose.yml