HAProxy – How to Forward Client’s IP Address to Nginx in TCP Mode

I want to forward real client's ip address from haproxy to my backend servers in tcp mode. The configuration of Haproxy is as follows:

frontend main
    bind *:80
    mode http
    option forwardfor
    option http-server-close    
    default_backend app-main

frontend https_main
    bind *:443
    mode tcp
    option tcplog
    option tcpka
    default_backend app-ssl

backend app-main
    balance roundrobin
    server web1 192.168.1.22:8080 check fall 3 rise 2
    server web2 192.168.1.33:8080 check fall 3 rise 2

backend app-ssl
    balance roundrobin
    mode tcp
    option ssl-hello-chk
    server web3 192.168.1.44:443

backend servers for http requests are apache and I have replaced the following line in httpd.conf with log lines, so I can now get the client's ip addreses correctly:

LogFormat "%h %l %u %t \"%r\" %>s %b %{X-Forwarded-For}i" common

My backend server for https uses Nginx as a reverse_proxy for ssl termination and sends the requests to apache backends. My problem is that I don't know how can I get the real client's ip address in nginx logs? I googled a lot and found some solution on serverfault and stackoverflow, but none of them resolved my problem in forwarding client's ip address in tcp mode in haproxy. Any help is appreciated.