Fetch the repository packages from Percona web:
wget https://repo.percona.com/apt/percona-release_0.1-4.$(lsb_release -sc)_all.deb
Install the downloaded package with dpkg. To do that, run the following commands as root or with sudo:
dpkg -i percona-release_0.1-4.$(lsb_release -sc)_all.deb
Once you install this package the Percona repositories should be added. You can check the repository setup in the /etc/apt/sources.list.d/percona-release.list file.
Remember to update the local cache: