My preference would be to use split. I would split on patterns like ") AND (" and ") OR (" which would guard against capitalized AND or OR appearing in your random string and remove the parentheses as well.

use strict;
use warnings;
use Data::Dumper;

my $str1 = q!AND (random text) AND (more random text) AND (yet more)!;
my $str2 = q!OR (random text) OR (more random text) OR (yet (more))!;

for ( $str1, $str2 ) {
    my @texts = grep $_          # filter out empty strings
        , split /
                 (?:\)\s|^)      # either closing parentheses or start
+ of string
                 (?:AND|OR)\s\(  # followed by AND or OR and opening p
+arentheses
                 |               #   or 
                 \)$             # closing parentheses at end of strin
+g
                /x;
    print Dumper \@texts;
}
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