Note that you might replace strings you don't want them to be replaced.
INSERT INTO @test-2(TEST_STRING)
VALUES
('I am a bad Gal')
,('I am a good Gal')
,('Oh my goodness! There''s no more goodwill')
,('He''s a patient with Osgood–Schlatter disease');
SELECT
*, REPLACE(TEST_STRING, 'good', 'bad')
FROM @test-2 T
WHERE T.TEST_STRING LIKE '%good%';