Connecting to Oracle DB with LDAP-Credentials

So I would like to connect to a remote Oracle database from my Linux system using the oraclient 19c on the command line, but whenever I try to connect it sees the realmpart of my username as the server. For example I want to connect with my username "USER@REALM.DOMAIN" to the database identified by "DB" in my tnsnames.ora, i do sqlplus USER@REALM.DOMAIN@DB and of course it complains with ORA-12154: TNS:could not resolve the connect identifier specified, because it thinks "REALM.DOMAIN" is the database. When I try it without the realmpart like sqlplus USER@DB it returns ORA-01017: invalid username/password; logon denied. How can I pass my username to the client?