Download client lib from here (Base + sqlplus + SDK). Unzip all in /opt/oracle

/etc/profile.d/oracle.sh

export ORACLE_HOME=/opt/oracle
export PATH=${PATH}:/opt/oracle

/etc/ld.so.conf.d/oracle.conf

/opt/oracle

adjust library names

cd /opt/oracle
ln -s libclntsh.so.10.1 libclntsh.so
ln -s libocci.so.10.1 libocci.so

run sudo ldconfig

add to .bashrc

alias sqlplus="rlwrap sqlplus"