Find/replace within option values with SQL in phpmyadmin

What’s the correct query to find and replace options values? I need to find/replace a bunch of URLs in option_values of an option_name called widget_text

I changed all URLs in options with this:

UPDATE bierken_options SET option_value = replace(option_value, 'http://www.olddomain.com', 'http://www.newdomain.com') WHERE option_name = 'home' OR option_name = 'siteurl';

but that didn’t get the widget text, and Search Regex doesn’t pick up the widget text, either.