$ wp search-replace 'site1.fi' 'site2.fi'
First parameter is the old URL and second parameter is the new URL
If you want to see the report without applying changes add --dry-run
flag like in example below.
$ wp search-replace 'site1.fi' 'site2.fi' --dry-run
Changing site url in WordPress multisite
$ wp search-replace 'site1.fi' 'site2.fi' --url='site1'
Read more about wp search-replace