Installation of Oracle Instant Client on an Ubuntu 64 machine
Easily solved:

export ORACLE_HOME=/usr/lib/oracle/12.1/client64
export PATH=$ORACLE_HOME/bin:$PATH
export LD_LIBRARY_PATH=$ORACLE_HOME/lib:$LD_LIBRARY_PATH


Stick those lines in your ~/.bash_profile if you want them to persist for a given user, or in /etc/bashrc to persist for all users.