Complex sentence: Penn's clients have included political and business leaders, including U.S. President Bill Clinton, British Prime Minister Tony Blair, and Microsoft Chairman Bill Gates; he also served as chief strategist and pollster to Hillary Clinton in her 2008 presidential campaign.
Split into simpler sentences: Penn's clients included political and business leaders, including U.S. President Bill Clinton, British Prime Minister Tony Blair, and Microsoft Chairman Bill Gates. Penn also served as chief strategist and pollster to Hillary Clinton in her 2008 presidential campaign.