It would be worth opening a Tech Support Track to work through the steps you are unsure about. Viya 4 is still pretty new and there aren't a lot of Community users with the firsthand experience to help. Also Viya 4 seems to be using more of a cloud-based SaaS delivery model which doesn't help those who prefer a more DIY approach 😉
Feel free to post additional details back in this post. I'm interested as Viya 4 is on our radar along with many others.
Generally speaking, you need the client to be on a file system we can mount into any pods that need it. Often this is done using the NFS server deployed by the IAC. You create a path for the Oracle client within the NFS share, extract the oracle client there, and then use the sample data-access YAML files to mount the NFS to the pods as needed. Then you define the environment variables with the sas-access.properties file to point to the mounted path. The README.md file in $deploy/sas-bases/examples/data-access has more detail on this, or $deploy/sas-bases/docs/configuring_sasaccess_and_data_connectors_for_sas_viya_4.htm if you'd like to view it with a browser.
Here's a link to the HTML doc from the latest stable release: