When I'm trying to submit search form from keyboard - it doesn't work, but if I just click to value in drop-down - it works as expected.

Hello, @ihor-sviziev. Based on Your issue an internal ticket was created - MAGETWO-70961. As the issue is fixed You'll be informed. Thank You for reporting.
@ihor-sviziev, thank you for your report.
We've created internal ticket(s) MAGETWO-70961 to track progress on the issue.
I'm working on it #SQUASHTOBERFEST
@romainruaud could you please accept the invitation to magento/magento2 on the GitHub?
@okorshenko done !
Internal ticket to track issue progress: MAGETWO-81146
The issue has been fixed in 2.2-develop branch and will be available with 2.2.2 release soon
Hi @ihor-sviziev. Thank you for your report.
The issue has been fixed in magento-engcom/magento2ce#1284 by @magento-engcom-team in 2.3-develop branch
Related commit(s):
The fix will be available with the upcoming patch release.
Is there any way to search complete string instead of each word? For example i want to search customer with full name but i get results based on first name
@shachiarkatkar AFAIK no