nodejs get request header from Nginx

nodejs get request header from Nginx

I'm using nginx to proxy my nodejs app. In my app, I always asking a
"client_id" from header. When I'm doing the local test. Everything working
correct. But when I push to server and proxy by Nginx. Then the client_id
lost. I can see that when nginx do the proxy, it remove my custom header
"client_id".
What I want to ask is:
is there a way to make sure nginx can pass my client_id to nodejs?
is there a way can make nginx pass whatever the custom headers?