Steps to reproduce

1. Have a user with display name "Martin Rys"
2. Go to https://cloud.example.com/settings/users as an admin and try to search for "Rys"
3. 0 results

Expected behaviour

"Martin Rys" should pop up because "Rys" is part of the string "Martin Rys"

Actual behaviour

No results. Doing "*Rys" gets the result but that is far from intuitive.

Server configuration

Operating system: Ubuntu 18.04

Web server: Nginx

Database: MariaDB

PHP version: 7.2.10

Nextcloud version: 15.0.2

Updated from an older Nextcloud/ownCloud or fresh install: Originally NC 12

Where did you install Nextcloud from:
Manually.

Client configuration

Browser: Firefox 65

Operating system: Arch Linux

Logs

N/A, will provide if they're actually needed for the search issue.