How to get the certificate of the Client

How to get the certificate of the Client

A client sends data to a server over an SSL-encrypted connection. I want to see the client certificates that are sent to the server.

I got the server certificate with:

openssl s_client -connect 192.168.254.208:40004 </dev/null 2>/dev/null | openssl x509 -outform PEM > cert.pem

But how to get the client cert?

Is this possible with openssl s_server?

or can I use a simple python ssl-socket? (I have access to the certificates and keys from the server.) I only want to know which certificate the client sends.