A GIANT in public relations is spinning in a new direction, reshaping itself in significant ways that underscore how agencies of all kinds are being made over to better serve marketer clients in the 21st century.

Fleishman-Hillard, which was founded in 1946 as Fleishman, Hillard & Associates, will rebrand itself this week as FleishmanHillard, with elements that include a new logo and a new slogan, “The power of true” — no relation, presumably, to “Truth well told,” the slogan of McCann Erickson Worldwide, or “Truth and design,” the slogan of MediaVest.

Truth be told, the changes at FleishmanHillard — with worldwide revenue of more than $500 million and 2,500 employees — are meant to signal how it is striving to become an integrated marketing communications agency that offers services like advertising and social media marketing in addition to public relations.

“ ‘True’ is the central concept we’re rebranding on, to deliver on our promises to be the trusted adviser to guide you through the maze of choices,” said Dave Senay, president and chief executive at FleishmanHillard in St. Louis, which since 1997 has been part of the Diversified Agency Services unit of the Omnicom Group, the second-largest agency holding company after WPP.